01 Introduction University of

Document Sample

```					University of Central Punjab

CS1204 – Lecture 1

Introduction

Prof. Engr. Ahmed Hafeez
Faculty of Information Technology
In Learning THE PROCESS is more
important then THE RESULTS!
• Problem solving techniques and skills can only be acquired
through practice and through the study of increasingly more
difficult problems. The assignments all involve problem
solving. It is very important that you understand how you
solved the problem.
• HOW – is more important then DO
Everyone will ask if you can solve problems
• This requires individual study – beyond class and Lab.
• I cannot learn for you! (SORRY…)
• I will do my very best to help you through THE PROCESS!
HOW TO SUCCEED
• DO THE LAB EXERCISES AND ALL THE
ASSIGNMENTS!
• DO EXTRA EXERCISES (basis for
understanding!) 10% inspiration – 90% practice!
• WE WILL LEARN TOGETHER HOW TO
THINK. Capture the essence about the topic – so
you can solve similar problems based on what you
learned!) – [Thinking – vs. memorizing…].
• PARTICIPATE!
Ground Rules (so the Process runs best)
• Cellular phones „OFF‟ during class
• No side talking during class
to do so
• ?? What do you wish to add…
• Ground Rules are negotiable – but only before they
are broken
Digital Electronics
• Digital Electronics represents information (0, 1) with
only two discrete values.
• Ideally
“no voltage” (e.g., 0v) represents a 0 and
“full source voltage” (e.g., 5v) represents a 1
• Realistically
“low voltage” (e.g., <1v) represents a 0 and
“high voltage” (e.g., >4v) represents a 1
• We achieve these discrete values by using switches.
• We use transistor switches, which operate at high speed,
electronically, small in size.
Analog versus Digital

• Analog systems process time-varying signals that
can take on any value across a continuous range
of voltages (in electrical/electronics systems).
• Digital systems process time-varying signals that
can take on only one of two discrete values of
voltages (in electrical/electronics systems).
– Discrete values are called 1 and 0 (ON and OFF,
HIGH and LOW, TRUE and FALSE, etc.)
Representing Information Electronically

• A light bulb has to represent 4 different
information:
Bulb off -        no student inside
Bulb 1/3 lit -    1 student inside
Bulb 2/3 lit -    2 student inside
Bulb Full lit -   3 student inside

• A light bulb has to represent 10 different
information:
– Is it possible to differentiate the ten different light
intensity?
Representing Information Electronically
• A light bulb has to represent 2 different information:
Bulb off -         no student inside
Bulb Full lit -    1 student inside

• A light bulb has to represent 4 different information:
– How? With one bulb?
– Use two bulbs

• A light bulb has to represent 10 different information:
– Use four bulbs
Representing Information Electronically
• “Analog electronics” deals with non-discrete values

• “Digital electronics” deals with discrete values
Benefits of Digital over Analog
•   Reproducibility
•   Not effected by noise means quality
•   Ease of design
•   Data protection
•   Programmable
•   Speed
•   Economy
Digital Devices

•Gates
•Flip-Flops
•PLDs
•FPGAs
Gates
• The most basic digital devices are called gates.
• Gates got their name from their function of
allowing or blocking (gating) the flow of digital
information.
• A gate has one or more inputs and produces an
output depending on the input(s).
• A gate is called a combinational circuit.
• Three most important gates are: AND, OR, NOT
Digital Logic
• Binary system -- 0 & 1, LOW & HIGH.
• Basic building blocks -- AND, OR, NOT
AND, OR, NOT Gates
Flip-flops
• A device that stores either a 0 or 1.
• Stored value can be changed only at certain times
determined by a clock input.
• New value depend on the current state and it‟s
control inputs
• A digital circuit that contains flip-flops is called a
sequential circuit
Flip-flops

S-R latch symbols                    D flip-flop

J-K flip-flops
Integrated Circuits
• A collection of one or more gates fabricated on a
single silicon chip is called an integrated circuit
(IC).
• ICs were classified by size:
–   SSI - small scale integration - 1~20 gates
–   MSI - medium scale integration - 20~200 gates
–   LSI - large scale integration - 200~200,000 gates
–   VLSI - very large scale integration - over 1M
transistors
• Pentium-IV - 55 million transistors
DIP Packages
Gates in ICs
Programmable Logic Devices
• PLDs allow the function to be programmed into
them after they are manufactured.
• Complex PLDs (CPLD) are a collection of PLDs
on the same chip.
• Another programmable logic chip is FPGA -
field-programmable gate arrays.
CPLDs and FPGAs
CPLD                FPGA
Application Specific ICs (ASICs)
• Chips designed for a particular application are
called semicustom ICs or application-specific ICs
(ASICs).
• ASICs generally reduce the total component and
manufacturing cost of a product by reducing chip
count, physical size, and power consumption, and
they often provide higher performance.
• But costly if not produced in bulk.
Printed-Circuit Boards
• An IC is normally mounted on a printed-circuit
board (PCB) that connects it to other ICs in a
system.
• Individual wire connection or traces can be as
narrow as 4 mils with 4 mils spacing (one-
thousandth of an inch)
• Now a days, most of the components use surface
mount technology.
• They are normally layered.
Software Aspects of Digital Design
• Today software tools are an essential part of digital
design.
• Software tools improve productivity, correctness and
quality of designs
• Software tools are:
– Schematic entry
– HDL (Hardware Description Language) Editors
– Simulators - to verify the behaviour of the design
– Synthesis tools - circuit design
– Timing analyzers and verifiers
Digital Design Levels
• the lowest level of design is device physics and
IC manufacturing processes.
• design at the transistor level
• level of functional building blocks
• level of logic design using HDLs
• computer design and overall system design.
Different Design Levels
Consider a simple design example:

Build a multiplexer with two data inputs A and B, a
control input S, and an output Z.

Switch model for the example multiplexer
Designing at the transistor level
• Transistor-level
circuit diagrams

• Gate symbols (for simple elements)
• Logic design
using Truth tables
• Logic design
using boolean algebra
Equations: Z = S A + S  B

• Logic diagrams
• Prepackaged building blocks, e.g. multiplexer
Structural HDL program for the multiplexer
________________________________________
//Dataflow description of 2-to-1-line multiplexer
module mux2x1_df (A,B,select,OUT);
input A,B,select;
output OUT;
assign OUT = select ? A : B;
endmodule
_________________________________________
Summary
•   Design to minimize cost.
•   Rule of thumb is to minimize the number of ICs.
•   Though PLDs costs more but uses less PCB area.
•   Unless mass production avoid ASIC design.
•   Design to solve real life problems.

```
DOCUMENT INFO
Shared By:
Categories:
Stats:
 views: 5 posted: 2/13/2010 language: English pages: 33
How are you planning on using Docstoc?